1. Field of the Invention
The present invention described herein generally relates to ultra-low-field nuclear magnetic resonance methods and, more particular, to ultra-low-field nuclear magnetic resonance methods in which an external excitation magnetic field is replaced with a bio-oscillating magnetic field.
2. Description of the Related Art
Many heart diseases are caused by reentry excitation or ectopic excitation of myocardium. Such a conduction abnormality develops atrial arrhythmia, tarchycardia, and heart failure that cause a stroke. Moreover, myocardial conduction abnormality is the mechanism of ventricular fibrillation that causes sudden cardiac death resulting from cardiac arrest. Conventionally, in order to detect myocardial conduction abnormality, a catheter electrode is inserted through aorta and vena cava of the thigh to measure endocardial potentials one by one while changing positions. Alternatively, a multi-channel electrode patch is attached to the epicardium during thoracotomy surgery to measure the endocardial potentials. A non-invasive method includes electrocardiogram (ECG) in which a plurality of electrodes are attached to thorax and limbs to measure a potential and magnetocardiogram (MCG) in which myocardial electrical activity is measured using an ultra-sensitive magnetic sensor such as a superconducting quantum interference device (SQUID) or an atomic magnetometer.